HomeMy WebLinkAbout2021-12-09; Tierra Del Oro Street Water Main Impact Update (District 2); Gomez, PazTo the members of the:
PTY COUNCIL
Date0 li/2j CA ✓ CC V
CM V'Ti.CM _v DCM (3) V
CMWD Board Memorandum
Dec. 9, 2021
To: Carlsbad Municipa
From:
Vicki Quiram, General
r District Board of Directors
a ager, Public Works
Via: Scott Chadwick, Execu ive nager
Re: Tierra Del Oro Street a r Main Impact Update (District 2)
Ccarlsbad
Municipal Water District
Memo ID #2021226
This memorandum provides an update to a previous CMWD Board Memorandum dated
May 27, 2021, (Attachment A), on the water main serving Tierra Del Oro Street.
Background
On May 27, 2021, staff provided a CMWD Board Memorandum on the water main serving the
homes on Tierra Del Oro Street. In 2020, the existing water main had been damaged five times in
two months, mainly by private contractors. Each incident required an isolation of the water main
to allow for repairs, resulting in a temporary shutdown of water for the residents (approximately
20-30 single family homes).
The existing water main on Tierra Del Oro Street, which is a 4" diameter asbestos concrete pipe,
or ACP, distribution main was installed in June 1967. The depth of the line ranges from
approximately 12" to 24". Current engineering standards require water mains to be a minimum
of 8" diameter, PVC material and a minimum depth of 42" from the finished surface to the top of
the pipe. The larger pipe diameter and increased coverage provide protection of the pipe from
potential damages and breaks.
Discussion
Staff reviewed factors such as the age of the pipe, number and cause of breaks, location and
consequence of failure when making decisions about whether and when to replace the pipe and
the priority for doing so. Testing performed on a pipe sample showed that the pipe is at the end
of its useful life.
With this data, replacement was made a higher priority and it was added to a pipe replacement
project that was being designed (Capital Improvement Program (CIP) Project No. 3904-C,
Downtown and Terramar Small Diameter Water Main Replacement project). The entire CIP 3904-
C project will replace approximately 4,440 linear feet (LF) of aging pipeline in six separate
locations, with approximately 800 LF pipe replaced on Tierra Del Oro Street.
Carlsbad Municipal Water District
5950 El Camino Real I Carlsbad, CA 92008 I 760-438-2722 t
Board Memo -Tierra Del Oro Street Water Main Impact Update (District 2)
Dec.9,2021
Page 2
Next Steps
The project is nearing design completion. The following summarizes the tentative schedule for
remaining design work, bid and project construction:
• December 2021: Consultant provides 90% design submittal, and the state's Division of
Drinking Water reviews submittal
• January 2022: CMWD staff provide design comments to the consultant, and the city's
Planning Division completes formal review
• February 2022: Consultant completes 100% design submittal
• March 2022: Staff request the CMWD Board's approval of plans and specifications and
authorization to bid the project
• June 2022: Staff request the CMWD Board's approval of construction contract award
• Fall 2022: Estimated construction start
• Summer 2023: Estimated construction completion
Construction in the fall is recommended based on the remaining design work to be completed
and given the location of pipe segments in seasonally congested areas in the city. Additionally,
there is a pipe segment north of the Tierra del Oro Street location that serves a marine research
center with higher constant water demands in the spring and summer research periods.
The CIP Project 3904-C, which includes the Tierra Del Oro Street portion, was recently removed
from the city's Terramar Area Coastal improvements project to expedite the needed water line
replacement. CMWD staff are coordinating with the Transportation Department staff on the
shared work and costs of the subsequent repaving following pipe replacement. The planned
slurry sealing of Tierra Del Oro Street for the affected area will be delayed until completion of the
waterline project and will be included the subsequent slurry seal project.
Attachment: A. Board Memorandum dated May 27, 2021
cc: Geoff Patnoe, Assistant Executive Manager
Celia Brewer, General Counsel
Laura Rocha, Deputy City Manager, Administrative Services
Robby Contreras, Assistant General Counsel
Tom Frank, Transportation Director/City Engineer
Ryan Green, Finance Director
Kristina Ray, Communication & Engagement Director
Dave Padilla, District Engineer
Babaq Taj, Engineering Manager
Hossein Ajideh, Engineering Manager
Keri Martinez, Utilities Senior Engineer
Valerie Airey, Municipal Projects Manager
To the members of the:
CITY COUNCIL
Date ~CA v CC ✓
CM ~ ACM _.!L_ DCM (3) v
May 27, 2021
CMWD Board Memorandum
To: Carlsbad Municipal Water District Board of Directors
F.rom: Paz Gomez, Deputy City Manager, Public Works
Vicki Quiram, General Manager
Via: Scott Chadwick, Executive Manager {[iiJ
Re: Tierra Del Oro Street Water Main Impact Update (District 2)
ATTACHMENT A
Ccarlsbad
Municipal Water District
Memo ID #2021109
This memorandum provides an update on a previous Council Memorandum dated
J,m. 17, 2020, (Attachment A), on the water main serving Tierra Del Oro Street.
Background
On Jan. 17, 2020, staff provided a Council Memorandum on the water main serving the homes
on Tierra Del Oro Street. Some residents had expressed frustration because the existing water
main had been damaged five times in two months, mainly by private contractors. Each incident
required an isolation of the water main to allow for repairs, resulting in a temporary shutdown of
water for the residents (approximately 20-30 single family homes).
The existing wat~r main on Tierra Del Oro Street, which is a 4" diameter asbestos concrete pipe,
or ACP, distribution main, was installed in June 1967. The depth of the line ranges from
approximately 12" to 24". Current engineering standards require water mains to be a minimum
of 8" diameter, PVC material and a minimum depth of 42" from the finished surface to the top of
the pipe. The larger pipe diameter and increased coverage provide protection of the pipe from
potential damages and breaks.
Discussion
Common construction activities usually do not impact existing infrastructure at this high
frequency. While it is difficult to determine one factor that caused the breaks on Tierra Del Oro
Street, recent events suggest that the condition of the water main and the depth at which it was
installed over 50 years ago may have contributed to the recent breaks.
Staff reviewed factors such as the age of pipe, number and cause of breaks, location and
consequence of failure when making decisions about whether and when to replace the pipe and
the priority for doing so. Testing performed on the sample showed that the pipe is at the end of
its useful life. With this data, replacement was made a higher priority and it was added to a pipe
replacement project that was being designed (Capital Improvement Program Project No. 3904-C,
Downtown and Terramar Small Diameter Water Main Replacement project). The project is
nearing completion of design.
Carlsbad Municipal Water District
5950 El Camino Real I Carlsbad, CA 92008 I 760-438-2722 t
Board Memo -Tierra Del Oro Street Water Main Impact Update (District 2)
May 27, 2021
Page 2
Next Steps
Upon completion of design, staff will return to the CMWD Board to request approval of plans and
specifications and authorization to bid, which is expected to be in fall 2021. Construction is
expected to begin in the first quarter of 2022, with completion expected in summer 2022.
Attachment: A. Council Memorandum dated Jan. 17, 2020
cc: Geoff Patnoe, Assistant Executive Manager
Celia Brewer, General Counsel
Laura Rocha, Deputy City Manager, Administrative Services
Robby Contreras, Assistant General Counsel
Dave Padilla, District Engineer
Babaq Taj, Engineering Manager
Valerie Airey, Municipal Projects Manager
To the members of the:
CllY-COUNCIL
·Date 1/41 /'JD CA i cc¥.
CM L coo L DCM. {3) !:_,_
Jan. 17, 2020
To:
From:
Via:
Re: ·.
Council Memorandum
Honorable fv'.layor Hall and M·embers of the City Council
Pai Gomez, Deputy City Manager, Publii Works
Elaine Lukey, Chief Operations Officer tfr
Tierra Del Oro Water Main Impact ·
ATTACHMENT A
._·{cityof
Carlsbad
' Memo ID# 2020006
On Ja·n. 14, 2020, the water main serving the homes on Tierra Del Oro Street was isolated to
make a repair. This was the fifth service interruption in recent months. Some residents on ·
Tierra Qel Oro Street have exp~essed frustration with the outages. This memorandum provides
an update on recent events affecting the water main on Tierra Del Oro Street.
Background
The existing water main on Tierra Del Oro Street was completed in June 1967 and was installed
as a 4" Asbestos Concrete Pipe (ACP) distributi_on main. As observed in the field, the-depth of
the line ranges from approximately 12" t.o 24". Current City of Carlsbad Engineering Standards
no longer _allow 4" water main pipe nor the ·installation of ACP pipe. Current st~ndards require
water mains to be 811 diameter (minimum), polyvinylchloride (PVC) and installed at a minimum
d·epth of 42" from the top of the pipe to the finished surface. The larger pipe diameter and
increased·coverage provides protection of the pipe from damages and from breaks.
Currently, there are two separate private development projects for the construction of single-
family residence homes on Tierra Del Oro Street. Grading permit GR150017 was. issued to Mike
Lloyd Excavating and Thomas J. Taylor Construction for the construction of the home located at
· 5039 Tierra Del Oro Street (Site 1). Grading permit GR2017-0061 was issued.to Zavatto Brothers
Construction for the construction of the home located at 5015 Tierra Del Oro Street (Site 2).
In recent months, there have been five incidents involving the existing water main on Tierra Del
Oro Street. Each incident has required c!n isolation of the water main to allo\i'.lf for repairs
resu·lting in a temporary shutdown of water for the residents on "Tierra Del Qro Street
(approximatel_y 20-30 single family homes).
Discussion
_Below is a list and brief description of events from the five incidents that have resulted in a
water outpge to fadlit~te repairs:
1-Site 1: A fence .post impacted a water main in private property at the edge of right-of-
way. The .line impacted was a 4" ACP pipe at a depth of18". Had the water main been
installed per current standards,.it is likely the fence post ~ould not have impacted the
line.
Public Works Branch
Construction Management & Inspection Department .
. Faraday Center 1635 Faraday Ave·.! Carlsbad, CA 92008 I 760-602-2730
Honorable Mayor Hall and Members of the City Council
Jan. 17, 2020 ·
Page 2
2-Site 1: The contractor was using a jumping jack tamper (commonly called a Wacker) to
compact soil in an open excavation approximately 5-ft from the subject 4" ACP water
main. The vibration from the activity caused a break in the pipe. The contractor did not
directly impact the water main and the water main was buried (confined in soil) at the
time of the incident. ·
3-Site 2: The contractor identified _an existing direct tap on the subject 4IIACP water main.
A direct tap t_o a collar is not allowed per the City of Carlsbad's Engine~ring Standards. ·
The· contractor submitted a Request for Information for direction on how to make the
repair. The contractor installed the new pipe section per CMWD's recommendation and
under the observation of the city's inspector. Following the installation, CMWD
energized the line and verified no leaks. Approximately 10 h<;>urs later (in the middle of
the night), the subject line broke nearby/adj~cent to the repair locatio~. The break was
not at the immediate repair location or within the excavation/trench limits of the repair.
4-Site 1: The contractor mobilized a boom (crane) truck to install a tree as a part·of the
close-out/ landscape phase of work. The boom truck's outrigger was plac~d on a
secondary crane pa·d on privat~ property at the edge of right-of-way. As _the boom truck
swung its load (tree) into position the ground beneath the crane pad settled
compromising the subject 4" ACP water main. The impacted line was approximately 18"
deep. · ·
5-Site 1: On Tuesday, Jan. 14, 2020, CMWD received a report of a ruptured water line.
Upon i3rrival, the city's inspector igentified the compromised water line to be the
subject 4" ACP water main. The location of the break was under a finished (completed)
driveway. No inspections were scheduled for the day and the contractor's
superintendent stated that no construction activity took place that day.
It is not typical fc;>r the common construction activities listed above to cause harm or to impact
e;istlng infrastructure such as a water main. While it is difficult to definitively determine any
one causa! factor for the recent breaks on Tierra Del Oro Street, recent events suggest that the
condition of the water main, and the depth in which it was installed over 50 years ago, may
have likely contributed to the recent breaks.
Next steps
When a water main is impacted, CMWD reviews the causal factors of the ii:npact to determine
mhigation measures. If/when multiple breaks occur on any given water main, CMWD reviews
those mains for possible inclusion in its pipeline replacement program. Staff reviews factors
such as the age of pipe, number and cause of breaks, location and consequence of failure whe_n
making decisions about whether to replace mains and the priority for do_ing so.
According to CMWD's Maintenance & Operations Division, the recent breaks on the Tierra del
Oro Street wat_er inain may likely be the result of the shallow depth at which the pipe is buried,
making it more susceptible to pr.obi ems when ground disturbing activities (such as construction,
heavy vehicles-or vibration.s) occurs nearby.
2
Honorable Mayor Hall and Members of the City Council
Jan.17,2020
Page 3
The subject pipeline was c;onstructed in 1967 and, due to recent events,.has been observed to
have a shallow depth of burry rangingfrom 12" to 24". 'Given the age of the pipe, location,
depth and the number of recent breaks, CMWD has determined that this water rr_iain is a
candidate for replacement and has given this project to Utilities Engineering staff to be included
on the·list of water main replace_ment projects.
Additionally, a pipe sample was taken from the main break that occurred on Jan. 14, 2020. The
sample will be seht to a lab for testing to determine remaining useful life .. This, along with the·
criteria mentioned above, will be used to determine the priority for replacing the water main.
cc: Scott Chadwick, City Manager
Celia Brewer, City Attorney
Vicki Quiram, Utilities Director
Ken Knatz, Engineering Man~ger
Babaq Taj, Engineering Manager
Amanda Guy, Deputy City Attorney
Valerie Airey, Municipal Projects Manager
3
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